This invention pertains to molded closures for containers. More particularly, this invention pertains to directly injection molding a closure onto a container.
Consumers have come to recognize and appreciate resealable closures for containers to store, for example, liquid food products and the like. These resealable closures permit ready access to the product while providing the ability to reseal the container to prolong the life and freshness of the product. Typically, the containers or cartons are formed from a composite of paperboard material having one or more polymer coatings or layers to establish a liquid impervious structure.
In known containers having such closures, the closures, which are formed in a separate process and transported to the packaging process, are conventionally affixed to the containers as part of the overall form, fill and seal operation. Typically, the closures are affixed to the partially erected carton prior to filling the carton with product. One known method for affixing the closure to the carton uses an ultrasonic welding process. In this process, the carton is partially erected and the closure is brought into contact with the carton, overlying an opening in the carton. Subsequently, an anvil is placed against the carton material and an ultrasonic horn is brought into contact with a flange of the closure. The ultrasonic horn is actuated which ultrasonically welds the flange to the carton material.
Another method for affixing closures to cartons uses an induction heating process. In this process, again, an anvil is placed on the carton material and an induction sealing head is brought into contact with the flange. A current is induced in the induction sealing head which, again, results in welding the flange to the carton.
While these methods for affixing the closures to cartons work well for sealing pre-formed or pre-molded closures to containers, and while they do facilitate maintaining product freshness and container resealability, there are nevertheless drawbacks. For example, closure sourcing could have a significant adverse impact on product manufacture. That is, bottlers or dairies must maintain high inventories of closures to assure that a sufficient quantity is on-hand during the bottling operation. Typically, the closures are provided by a closure manufacturer or supplier. Thus, if the manufacturer or supplier cannot meet the required supply, product production (e.g., packaging) may have to be slowed or stopped until the required volume of closures can be obtained.
In addition, equipment is necessary for transporting and affixing the closures to the cartons. With respect to this equipment, components are necessary to transport the caps from a storage area to the carton and to, perhaps, properly orient the closures at the carton. Additional machine components are also needed to support the closure at the carton and to seal the closure to the carton.
Thus, as will be readily recognized, while such closures provide numerous benefits and advantages over known folded gable top spout arrangements, these closures can be rather costly, and may be too costly for use in lesser expensive products.
Accordingly, there is exists a need for an apparatus and method for providing resealable closures on cartons. Desirably, such an apparatus and method eliminates a packagers reliance on a closure supplier. More desirably, such an apparatus and method allows for eliminating those portions of a form, fill and packaging machine that are related to affixing a closure, such as by welding, to a carton.
A form, fill and seal packaging machine for forming, filling and sealing a carton molds a closure directly onto the carton. The machine includes a carton erection station that is adapted to receive a carton in a generally flat form and erect the flat form carton into a tubular form defining an internal carton region.
A direct injection molding station has an internal mold tool and an external mold tool. In a preferred embodiment, the internal tool is fixedly mounted and the external tool is configured to move between a first position in which the external tool is disengaged from the internal tool and a second position in which the external tool is engaged with the internal tool with the carton disposed therebetween. In a most preferred embodiment, the external tool is formed having first and second portions configured to move toward one another when the external tool moves to the second position, and away from one another when the external tools moves to the first position.
The internal mold tool is configured for receipt within the internal carton region. The internal mold tool and the external mold tools are configured to receive and clamp the carton therebetween.
The direct injection molding station further includes a polymer injection system for injecting polymer from a location external of the carton to the internal mold tool, thus is directly molding a closure in place on the carton.
The machine further includes a filling station for filling the carton and a sealing station for forming a seal on the carton.
The polymer injection system can be configured to include a charging cylinder and an injection cylinder in series with one another. The charging cylinder provides a feed of polymer to the injection cylinder. Most preferably, the charging cylinder and the injection are in opposed relation to one another and are separated by a non-return valve.
In a preferred embodiment, the machine includes a sprue bushing in flow communication with the injection cylinder and a needle reciprocable within the sprue bushing for initiating and terminating flow of polymer to the internal tool.
To effect proper temperature control of the tools and the closure during formation, the internal and external mold tools include cooling channels. Heat transfer is maximized in an internal tool having cooling channels having a V-shaped configuration.
In the machine, a frame is mountable to the packaging machine, and a mandrel is mounted to the frame, on which the carton is mounted, and secured by the molding tools, during molding of the closure. Preferably, the internal mold tool is mounted to the mandrel.
A method for forming a closure on a carton blank in a tubular form, in which the carton blank is formed from a composite material having a polymer layer on at least one side thereof, includes the steps providing a fixed mold tool defining a portion of a mold cavity therein, the mold tool being in flow communication with a polymer injection system, positioning the carton blank adjacent and engaged with the internal tool, the carton blank being in an at least partially erected state having a tubular form, and providing a movable tool defining another portion of the mold cavity therein, the fixed tool mold cavity and the movable tool mold cavity defining a desired closure configuration
The method further includes the steps of engaging the movable tool with the carton blank on an opposing side of the carton blank from the internal tool, pressing the movable tool to the carton blank and the fixed tool, injecting a polymer into the mold cavity to form the desired closure, and releasing the carton with the closure molded thereon.
Other features and advantages of the present invention will be apparent from the following detailed description, the accompanying drawings, and the appended claims.